The CNS HIV Antiretroviral Therapy Effects Research (CHARTER) was funded in 2002 with the aim of exploring the changing presentation of HIV neurological complications in the context of highly active antiretroviral therapy (HAART). The six performance sites of CHARTER (Johns Hopkins University, Mt. Sinai Medical School, University of California at San Diego, University of Texas Medical Branch at Galveston, University of Washington, Washington University at St. Louis), representing a diverse participant pool as well as investigators with expertise in various aspects of NeuroAIDS, were able to standardize neuromedical, neuropsychological, psychiatric, neuropathy, and imaging protocols along with on-going quality assurance procedures. Two key conclusions to emerge from the CHARTER project are that HIV-Associated Neurocognitive Disorders (HAND) and peripheral neuropathy remain highly prevalent despite effective HIV treatments that have significantly reduced mortality and non-neurologic morbidities. In CHARTER Extension, 180 participants (30 per site) from the original CHARTER longitudinal cohort have been selected for further study based on the goal of shedding light on CSF virologic failure, low-level HIV replication, worsening cognition and abnormal white matter, as well on-going peripheral neuropathy. These individuals will be assessed annually using well-established neuropsychological, neuromedical, laboratory, and neuropathy assessments. A subset of participants will complete annual brain MRI scans.